Original Paper

Journal of Superconductivity and Novel Magnetism

, Volume 27, Issue 1, pp 195-201

Impedance Spectroscopy Properties of Pr0.67A0.33MnO3 (A = Ba or Sr) Perovskites

  • S. HciniAffiliated withLaboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir, Université de Monastir Email author 
  • , S. KhadhraouiAffiliated withLaboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir, Université de Monastir
  • , A. TrikiAffiliated withLaboratoire des Matériaux Composites, Céramiques et Polymères, Faculté des Sciences de Sfax, Université de Sfax
  • , S. ZemniAffiliated withLaboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir, Université de Monastir
  • , M. BoudardAffiliated withLaboratoire des Matériaux et du Génie Physique, Grenoble INP, CNRS (UMR 5628), MINATEC
  • , M. OumezzineAffiliated withLaboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir, Université de Monastir

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Abstract

We have investigated the dielectric properties of Pr0.67Ba0.33MnO3 (PBMO) and Pr0.67Sr0.33MnO3 (PSMO) perovskites synthesized by the solid-state reaction method at 1473 K. Samples were characterized by complex impedance spectroscopy (CIS) in the frequency range from 40 Hz to 1 MHz, at room temperature. The conductivity curves for the two samples were well fitted by the Jonscher law σ(ω)=σ dc + n . For the PBMO sample, the hopping process occurs at long distance, whereas for PSMO compound it occurs between neighboring sites. Frequency dependence of dielectric constant (ε″) and tangent loss (tanδ) show a dispersive behavior at low frequencies that was explained on the basis of the Maxwell–Wagner model and Koop’s theory. Electric modulus formalism has been employed to study the relaxation dynamics of charge carriers. For both compounds, the variation of the imaginary part Z″ shows a peak at a relaxation angular frequency (ω r ) related to the relaxation time (τ) by τ=1/ω r . Nyquist plots of impedance show the presence of two semicircles and an electrical equivalent circuit has been proposed to explain the impedance results.

Keywords

Perovskites Dielectric properties Impedance spectroscopy Grains and grain boundaries effects